A Web application penetration tester, Ebrahim Hegazy, has discovered a critical remote PHP code injection vulnerability in the Yahoo website that could allowed hackers to inject and execute any php code on the Yahoo server.

The vulnerability exists in the Taiwan sub-domain of the Yahoo "
http://tw.user.mall.yahoo.com/rating/list?sid=[CODE_Injection]". The 'sid' parameter allows to inject PHP code.

According to his blog post, the sid parameter might have been directly passed to an eval() function that results in the code Injection.

In his demo, Ebrahim showed how he to get the directories list and process list by injecting the following code:
http://tw.user.mall.yahoo.com/rating/list?sid=${@print(system(“dir”))}
http://tw.user.mall.yahoo.com/rating/list?sid=${@print(system(“ps”))}

He also found out that Yahoo server is using an outdated kernel which is vulnerable to "Local Privilege escalation" vulnerability.

Yahoo immediately fixed the issue after getting the notification from the researcher. However, he is still waiting for the Bug bounty reward for the bug. Google pays $20,000 for such kind of vulnerabilities. Yahoo sets the maximum bounty amount as "$15,000". Let us see how much bounty Yahoo offers for this vulnerability.